Head rest control systems

The present invention relates to head rest control systems that can control a distance between heads of passengers and head rests of vehicle seats by moving the head rests back and forth.

One known art for controlling movement of a head rest is taught by Patent Document 1. In this art, a collision prediction sensor, a head rest moving mechanism and a control device for controlling the head rest moving mechanism are used. The collision prediction sensor can predict a back-side collision of a vehicle a desired time (e.g., 1.0 second) before occurrence of the collision. The control device actuates the head rest moving mechanism in response to a signal from the collision prediction sensor, thereby moving the head rest forwardly from a normal position. As a result, the head rest moves closer to a head of a passenger so as to prepare a burden imposed on the passenger at the time of the back-side collision.

In a control of movement of the head rest as set forth in Patent Document 1, the vehicle must have the collision prediction sensor. In another known art, a thin plate-shaped capacitance sensor disposed in the head rest is used in place of the collision prediction sensor. The capacitance sensor may detect a relative position (distance) of the head rest relative to the passenger head without contact. The control device actuates the head rest moving mechanism in response to a signal from the capacitance sensor, thereby moving the head rest such that the distance between the head rest and the passenger head can be maintained constant.

An additional known art is taught by Patent Document 2. In this art, a head rest is constructed to move up and down in response to a signal from a capacitance sensor so as to follow a head of a passenger.

Patent Document 1: JP 2004-9891 A

Patent Document 2: JP 2000-309242 A

In order to deal with a collision, a vehicle without a collision prediction sensor can be provided with a control in which the head rest is moved in response to a signal from a capacitance sensor or other such sensors so as to follow a head of a passenger. However, in such a control, even if the head of the passenger moves slightly, the head rest can be moved in response to the motion of the passenger head. Such a motion of the head rest may cause discomfort to the passenger.

It is one object of the present invention to provide a control for moving a head rest in response to a signal from a sensor detecting a distance between the head rest and a head of a passenger, in which if the head of the passenger moves within a predetermined range, the head rest can be prevented from moving depending on the motion of the passenger head so as to remove discomfort for the passenger.

It is another object of the present invention to provide such a control, in which the head rest can be moved only in a predetermined period of time so as to increase a sense of use of the head rest.

It is further object of the present invention to provide such a control, in which the head rest can be moved only when the passenger head is continuously positioned outside of a proper range for a desired period of time so as to further increase the sense of use of the head rest.

It is further object of the present invention to provide such a control, in which the head rest moved to an optimal position when a back-side collision of a vehicle is expected can be prevented from affecting driving when the collision is avoided.

It is still further object of the present invention to provide such a control, in which ability to relieve a burden imposed on the passenger at the time of the back-side collision of the vehicle can be increased.

The invention described in claim 1 is a head rest control system in which a head rest of a seat of a vehicle is constructed to be moved back and forth by a head rest moving mechanism, which includes a sensor detecting a distance between the head rest and a head of a passenger, and a control device controllably actuating the head rest moving mechanism. The control device is constructed to actuate the head rest moving mechanism so as to move the head rest forwardly or backwardly when the distance between the head rest and the head detected by the sensor is outside of a proper range of clearance in which it is possible to deal with a back-side collision of the vehicle, thereby moving the head rest to a proper position in which it is possible to deal with the back-side collision of the vehicle.

According to the invention, even if the head of the passenger moves within the proper range of clearance in which it is possible to deal with the back-side collision of the vehicle, the head rest can be prevented from moving depending on the motion of the head of the passenger so as to prevent discomfort for the passenger. This may lead to an increased sense of use of the head rest. In addition, according to the head rest control system, it is possible to deal with the back-side collision of the vehicle even if the vehicle is not provided with a collision prediction sensor.

The invention described in claim 2 is the head rest control system as defined in claim 1, wherein a period of time in which it is necessary to deal with the back-side collision of the vehicle is determined, and wherein the control device is constructed to actuate the head rest moving mechanism only in the period of time, thereby moving the head rest to the proper position.

According to the invention, the head rest is moved only in a period of time in which it is necessary to deal with the back-side collision of the vehicle, e.g., a period in which the passenger fastens a seatbelt or a period in which the vehicle is running. This may further increase the sense of use of the head rest.

The invention described in claim 3 is the head rest control system as defined in claim 1, wherein the control device is constructed to actuate the head rest moving mechanism when the distance between the head rest and the head detected by the sensor is continuously outside of the proper range for a predetermined time, thereby moving the head rest to the proper position.

The invention described in claim 4 is the head rest control system as defined in claim 2, wherein the control device is constructed to actuate the head rest moving mechanism when the distance between the head rest and the head detected by the sensor is continuously outside of the proper range for a predetermined time, thereby moving the head rest to the proper position.